Conventionally, the printing heads of printers have been precisely positioned after adjusting the position thereof because good-quality printing characters cannot be obtained unless the distance between the printing hammer and the platen, which are on opposite sides of an ink ribbon and a sheet of printing paper is accurately established. For this purpose, a coiled spring for biasing the printing head rearwards is connected between the printing head and the carrier. Further, the printing head is arranged to be shiftable forwards step by step against the action of the coiled spring by the use of a counter-sunk screw or eccentric cam and then the head is held stationary in position. Therefore, a large space is required to install the coiled spring, and the structure of the device is complex.